Field of the Invention
The present invention relates to a photobiomedical measurement apparatus. More particularly, the present invention provides a photobiomedical measurement apparatus that noninvasively measures a brain activity.
Description of the Related Art
Industrial applications of the present invention provide a photobiomedical measurement apparatus that noninvasively measures brain activities.
To date, a brain function photo imaging apparatus that can conveniently and noninvasively measure a brain activity using light has been developed. According to such a brain function photo imaging apparatus, a light emission probe arrayed on the subject's scalp surface radiates near infrared (IR) light having three (3) different wave lengths λ1, λ2, λ3 (e. g. 780 nm, 805 nm and 830 nm) and a light receiving probe arrayed on the scalp surface detects a light intensity, A (λ4), A (λ2), A (λ3) (information of an amount of received light) of near infrared light having each wave length λ1, λ2, λ3 emitted from the brain.
Simultaneous equations showed as the relational equations (1), (2) and (3) are set using e. g. Modified Beer Lambert Law to obtain a product [oxyHb] of oxyhemoglobin concentration and light path length and a product [deoxyHb] of deoxyhemoglobin and light path length in the cerebral blood flow from A (λ1), A (λ2), A (λ3), the information of the amount of received light obtained in this manner, and then the simultaneous equations are solved (refer to Non-Patent Document 1, hereby incorporated fully by reference). In addition, a product ([oxyHb]+[deoxyHb]) of total hemoglobin concentration and light path length is calculated from the product [oxyHb] of oxyhemoglobin concentration and light path length and the product [deoxyHb] of deoxyhemoglobin and light path length.A(λ1)=Eo(λ1)×[oxyHb]+Ed(λ1)×[deoxyHb]  (1)A(λ2)=Eo(λ2)×[oxyHb]+Ed(λ2)×[deoxyHb]  (2)A(λ3)=Eo(λ3)×[oxyHb]+Ed(λ3)×[deoxyHb]  (3)
Meantime, Eo(λm) is an absorbance coefficient of oxyhemoglobin at the light having wavelength λm and Ed (λm) is an absorbance coefficient of deoxyhemoglobin at the light having wavelength λm.
Here, a relationship between the distance (channel), between the light emission probe and the light receiving probe, and the measurement region is illustrated. FIG. 6 is a cross section view illustrating a relationship between a pair of a light emission probe and a light receiving probe and a measurement region.
The light emission probe 12 is pushed to a light emission point t of the scalp surface of a subject and further a light receiving probe 13 is pushed to a light receiving point r of the scalp surface of the subject. And light is radiated from the light emission probe 12 and light emitted from the scalp surface is incident on the light receiving probe 13. At this time, light radiated from the emission point on the scalp surface t and light thereof passing the banana-shape (measurement area, see FIG. 6) reaches to the light receiving point r of the scalp surface. Accordingly, A (λ1), A (λ2), A (λ3), the information of the amount of the received light as to the measurement region m at the depth that is half of the distance of the shortest line along the scalp surface of the subject particularly between the light emission point t and the light receiving point r from the midpoint s of the shortest line along the scalp surface of the subject particularly between the light emission point t and the light receiving point r among the measurement areas can be obtained.
Meantime, a measurement region m is a brain region but there is the scalp skin existing outside of the brain so that, unfortunately, such as a medical doctor and/or a laboratory technician cannot determine the arrayed position of the light emission probe 12 and the light receiving probe 13 while confirming the brain position.
Therefore, the medical doctor and/or the laboratory technician determines the arrayed position of the light emission probe 12 and the light receiving probe 13 based on the reference point set on the scalp surface but, unfortunately, they do not determine the arrayed position of the light emission probe 12 and the light receiving probe 13 based on the brain position. In addition, for example, the International 10-20 System Law is known as the reference points set on the scalp surface (see e. g. Non-Patent Document 2, the entire contents of which are herein incorporated by reference).
However, unfortunately, the human-brain shape is actually skewed and unsymmetrical in many humans. Therefore, despite unsymmetrical human brain, when the brain activity is measured at where the positions of the arrayed position of the light emission probe 12 and the light receiving probe 13 are arrayed evenly as to the scalp surface, it is further problematic that the brain activity of the brain region to be measured would not be measured.
In addition, the anatomical structure of individual brain is different from person to person. Specifically, since the brain shapes are different from person to person in many cases, the brain activity data measured based on the International 10-20 System Law could not been compared among plural people.
So, a photobiomedical measurement apparatus is disclosed in which a 3-dimensional configuration image can be image-displayed to show the positional relationship between scalp surface and brain surface to array a light emission probe 12 and a light receiving probe 13 and so forth. (See e. g. Patent Document 1, the entire contents of which are incorporated herein by reference.) FIG. 7 is a figure showing 3-dimensional configuration image showing the positional relationship between scalp surface and brain surface. Such photobiomedical measurement apparatus comprises a configuration image display means image-displaying 3-dimensional configuration image showing the positional relationship between a scalp surface image and a brain surface image, a measurement point determination means determining the predetermined point of the brain surface image as the measurement point m by designating a predetermined position of the brain surface image, and an estimated point determination means determining the specified point of the scalp surface image as an estimated point s and further image-displaying the estimated point s.
Therefore, according to such a photobiomedical measurement apparatus as proposed, such as a medical doctor and/or a laboratory technician can accurately array a light emission probe 12, a light receiving probe 13 and so forth while monitoring an image-display of a 3-dimensional configuration image showing the positional relationship between a scalp surface image and a brain surface image.